Bring a large pot of water to a boil.
Using a small, sharp knife, core the Brussels sprouts and separate the leaves. Salt the water and add all of the baby leaves to pot – you should have at least 6 cups, loosely packed. Count to 30, then drain and cold shock the leaves; drain them again.
Combine the lemon juice, grated or pasted garlic, anchovy paste, Worcestershire sauce, egg yolk (if using), lots of black pepper and EVOO to a bowl and whisk to make dressing. Whisk in the cheese once the dressing is emulsified.
Heat the butter in small skillet with the crushed garlic clove over medium heat. Add the breadcrumbs and toast to golden brown. Add the parsley and remove the garlic clove.
Toss the Brussels greens with dressing and breadcrumbs.